cover storyHannover Messe Hall 9, Stand H55
Robots with change tools or rotary tactics place high demands on the electrical connection technology. Weary contacts and connectors require short service intervals or even lead to machine downtime. With non-contact inductive couplers Turck Now an alternative to traditional connection technology: The NIC couplers transmit up to eight switching signals and IO-Link with up to 12 W power. This makes them a wear-free alternative to slip rings or mechanically stressed connectors.
Somehow, there is still something magical about placing a smartphone on a contactless charging station. Power transmission without cable? Technically, behind the principle of inductive coupling. The technology is not really new, but the mass use in the consumer area is still waiting. The charging function for electric toothbrushes and cordless phones remain the only mass-market applications to date.
Its strengths may rather play the inductive coupling for power transmission in the niche markets. For example, cardiac pacemakers and other medical implants are often inevitably equipped with the possibility of contactless current and signal transmission. The advantage here is obvious: Even the idea of a USB port on the chest to load the pacemaker reminds rather of horror or science fiction films than to reputable medical technology.
Absolute wear-freeHowever, a major advantage of the inductive coupling for signal and power transmission is hardly noticeable in these examples: Inductive coupling is absolutely wear-free. This advantage is rarely particularly important in private use, but in industrial use may be a key decision-making criterion. After all, the resulting longer maintenance intervals, shorter downtimes and higher cycle times of machines for buyers and production planners are powerful arguments.
Especially in applications in which contacts have to be plugged in and released very often, wear is a major problem - and thus a decisive cost driver. If manufacturers of connection and connection technology solutions to gild over contacts, the real need for wear-free solutions is clear. Just for the adornment nobody comes up with the idea to use gold. Although the precious metal minimizes the wear on the contacts, it can not prevent the process. Applications with heavy-duty connections, whether by vibration or frequent closing and disconnection of a connection, are thus very well suited for a 'non-contact plug connection'. Robots with change tools or rotary tables are examples of such applications.
Inductive couplers as non-contact connectors also impress with the freedom of movement they allow for the coupled components: for example, with robots with rotating tools or with shafts from which sensor signals must be led out. A contactless connection of the interface is of great advantage here. The slip ring as an alternative solution is indeed established in the industry, but is little appreciated due to its wear. Another field of application for inductive couplers are overhead monorail systems, which are frequently used in the automotive industry.
Amplifier-free coupler familyWith its NIC system, Turck now introduces a family of inductive couplers that can meet the challenges of these applications. The coupler sets each consist of a primary part on the control side and a secondary part on the sensor / actuator side of the connection. The NIC couplers transmit up to eight PNP switching signals and up to 500 mA high currents with 12 W power.
This allows sensors and actuators such as light curtains, piezo valves or smaller valve terminals to be operated without the need for an additional amplifier on the secondary side. The primary parts are connected via a four-pin M12 connector or an 30-cm pigtail with a 12-pin M12 connector. The abutment has an 30 cm pigtail with four-pin M12 connector. With 80 mm length, these couplers are among the most compact devices in the M30 package.
Three variants with IO-LinkThe inductive couplers can be connected as easily as a plug connection. A sensor or other signal source is connected to the secondary (NICS-M30-IOL2P8-0,3-RKC4.4T); the primary part (NICP-M30-IOL2P8X-H1141) is positioned opposite and connected to a controller or fieldbus device using a four-pin standard M12 connector. This basic system can transmit two PNP switching signals contactlessly behind the secondary coupler with a simple VB2 splitter. The air interface may be up to 7 mm wide.
The same system of primary and secondary couplers can also be used to transmit signals from measuring IO-Link-capable sensors. The primary coupler only needs to be connected to an IO-Link master. On the secondary side, the user accordingly connects an IO-Link sensor or any other IO-Link-capable device. These combinations even allow bidirectional IO-Link communication including all IO-Link features such as parameterization and diagnostic data. If the I / O hub (TBIL-M1-16DIP) for 16 digital PNP inputs is also connected on the secondary side, the system can also be used for identification, for example, at interchangeable tools. The hub transmits a unique ID to the controller via IO-Link.
The third solution variant is used when more than two signals are to be transmitted: In this case, the IO-Link protocol is used to transmit up to eight switching signals. Thus, eight PNP signals can be transmitted with one primary and one secondary part as well as an I / O hub. The twelve-pole primary coupler NICP-M30-8P8-0,3-RSC12T used here acts as IO-Link master, the I / O hub as slave. The primary part is connected to conventional PNP inputs of a fieldbus device via the M12 12 pin connector, so that the user does not even notice that the system works internally with IO-Link technology.
Diagnosis with metal detectionIn addition to the eight PNP sensor signals, the system provides two pins for diagnostic signals. One signal indicates the presence of the secondary part, the second serves for 'foreign object detection'. If foreign metal objects such as iron filings between primary and secondary coupler and reduce the transmission quality, the error signal is given to the controller, so that the error source can be located directly. The primary couplers with 4 pin connection display this diagnosis directly on site via visible status LEDs. If an IO-Link device is connected, the diagnostic data is also available in the controller.
Air interface and operational readinessThe inductive couplers with a maximum air interface of 7 mm and 12 W power transmission achieve the largest distance of all inductive couplers in this design. In addition, the devices are immune to shock and twisting of primary and secondary parts. If the primary and secondary parts are positioned directly opposite each other at the nominal distance, lateral offset up to 5 mm is possible.
If the application makes a linear mounting of the two coupler parts impossible, the coupler systems can also be mounted at an angle to each other. With 5 mm distance to each other an angle up to 15 ° is possible. Even with stronger inclines the signal does not break off directly. Although the performance is then increasingly weaker, but may still be sufficient depending on the application.
In many applications with frequently changing connections, the readiness time of the secondary part also plays a role. Especially in tool robot application, the cycle times that can be driven with the connection solution, a key decision criterion. The secondary section of the Turck coupler is ready for operation in less than 10 ms. The fixed primary part is permanently supplied anyway. With this start-up time, the system is one of the fastest on the market.
Of course, primary parts can be combined with any number of secondary parts and vice versa. With 'Dynamic Pairing' even complex applications with multiple primary and secondary parts can be solved problem-free.
The author Sander Makkinga is Product Manager Position and Proximity Sensors at Turck.